Mobile communication devices are becoming increasingly popular for business and personal use due to a relatively recent increase in the number of services and features that the devices and mobile infrastructures support. Handheld mobile communication devices, sometimes referred to as mobile stations, are essentially portable computers having wireless capability, and come in various forms. These include Personal Digital Assistants (PDAs), cellular phones and smart phones.
It is known in the art to provide Internet browser functionality in such mobile communication devices. In operation, a browser user-agent in the handheld mobile communication device issues commands to an enterprise or proxy server implementing a Mobile Data Service (MDS), which functions as an acceleration server for browsing the Internet and transmitting text and images to the mobile device for display. Such enterprise or proxy servers generally do not store the state of their clients (i.e. the browser user-agent), or if they do, the state that is stored is minimal and limited to HTTP state information (i.e. cookies). Typically, such enterprise or proxy servers fetch and transmit data to the browser user-agent when the browser makes a data request. In order to improve the performance of the browser on the mobile device, some enterprise or proxy servers fetch all the data required in order to fulfill the data request from the browser, aggregate the fetched data, and transmit the data to the device browser. For instance, if a HyperText Markup Language (HTML) page is requested, the enterprise or proxy server fetches any additional files referenced within the HTML page (e.g. Images, inline CSS code, JavaScript, etc.). Since the proxy server fetches all the additional files within the HTML file, the device does not have to make additional data requests to retrieve these additional files. Although this methodology is faster than having the device make multiple requests, the proxy server nonetheless has to send all of the data again if the site is later revisited. This is because the proxy server has no knowledge of the device caches (e.g. caches that are saved in persistent memory, for different types of data such as a content cache to store raw data that is cached as a result of normal browser activity, a channel cache containing data that is sent to the device by a channel or cache push, and a cookie cache containing cookies that are assigned to the browser by visited Web pages). For example, if a user browses to CNN.com, closes the browser to perform some other function (e.g. place a telephone call or access e-mail messages, etc.) and then later accesses the CNN.com Web site (or follows a link from CNN.com to a news story), the banner “CNN.com” will be transmitted from the MDS to the device browser each time the site is accessed, thereby consuming significant bandwidth, introducing delay, etc.
It is known in the art to provide local file caching. One approach is set forth in GloMop: Global Mobile Computing By Proxy, published Sep. 13, 1995, by the GloMop Group, wherein PC Card hard drives are used as portable file caches for storing, as an example, all of the users' email and Web caches. The user synchronizes the file caches and the proxy server keeps track of the contents. Mobile applications (clients) are able to check the file caches before asking for information from the proxy server by having the server verify that the local version of a given file is current.